They’re a symbol of good fortune…unless they mean your family’s in trouble. It’s taboo to kill them…unless an elder tells you to. The many myths surrounding the southern ground hornbill are often contradictory, but one thing’s for certain: this strange looking bird has a permanent perch in the African imagination.

Large and black, with eerie, raw-looking red skin around the eyes and throat sac, ground hornbills look a little like something out of a fairy tale…or a nightmare. Their appearance is even more unsettling when you take into account that the birds can grow to well over four feet in length, and generally travel in packs of up to 10 individuals, their black wings so broad that, looking up at a pack in flight, they briefly block out the sun.

Capable of living to 70 years in captivity, the birds are often strangely human. Breeding pairs are always assisted by at least two other animals (a sort of breeding apprenticeship that the hornbills must undergo if they’re to successfully breed later in life). Hatchlings are dependent on their parents for up to two years after birth, the longest period of any bird species. Even their faces seem anthropomorphized; they’re the only bird species to sport eyelashes.

These uncannily human traits, along with the booming, thunderous calls the birds use to communicate, make hornbills the focus of many myths throughout Africa. Many cultures consider the birds sacred. In these tribes, killing a hornbill is considered as grave a sin as murder, and doing so will bring down a deluge so great that it may wash your lands away in punishment.

Because of this belief—which is likely tied to the fact that in many regions, hornbills appear just before the long rains come—rain-doctors will sometimes ritualistically kill the birds in times of drought, attaching a stone to the body and throwing it into a stagnant pool in the river. According to myth, the birds are so smelly and unclean that they make even the lakes and rivers sick; sending rain is the only way the water can purge itself of these foul creatures, by washing them out to sea.

Besides being harbingers of rain (needed or otherwise), the creatures are considered accurate predictors of wealth. The spots where they feed are thought to be the best places to raise cattle, and are often sought out when new country is being settled. If a hornbill lands near your home, however, beware: unless it’s quickly chased off, a family member is sure to die (these beliefs may arise in part due to the ground hornbill’s diet, which often includes snakes; after a hornbill has visited pasture land, it may be safer for cattle, but seeing one near your home may be a sign of potential danger).

So are they good or evil? Should you avoid them out of fear, or seek them as a source of divine guidance?

Well that depends: how much do you like your windows?

Modern Africans are less likely to ascribe mystical powers to the birds than their forebears, but one hornbill behavior is indisputably detrimental to humans: their inability to recognize their own reflections.

If a hornbill sees itself reflected in a window, it will attack, convinced the reflection is in fact another hornbill (no wonder people are so afraid of them; their motto seems to be “attack first, figure out if it’s a real threat later). This has led to more than a few terrifying moments…and a lot of broken windows.

Which means the best way to make sure a hornbill brings you good fortune these days is to cover your windows with nets.